Electrolyzed hydrogen water systems, also known as electrolyzed oxidizing water (EOW) systems, have gained attention in the food processing industry as an effective sanitization method for equipment. These systems generate antimicrobial solutions through the electrolysis of water and dissolved salts, producing hypochlorous acid (HOCl) and other reactive oxygen species (ROS) that exhibit strong disinfectant properties. The technology offers advantages in microbial control, material compatibility, and operational efficiency compared to traditional chemical sanitizers.
The antimicrobial efficacy of EOW systems stems from the electrochemical reactions during electrolysis. A typical system uses a dilute salt solution, often sodium chloride, which is passed through an electrolytic cell with anode and cathode chambers. The anode produces acidic electrolyzed water (AEW) with a low pH (2.0–3.0) and high oxidation-reduction potential (ORP) above 1,000 mV, containing hypochlorous acid, chlorine, and hydroxyl radicals. These compounds disrupt microbial cell membranes, oxidize proteins, and degrade nucleic acids, leading to rapid inactivation of bacteria, viruses, and fungi. Studies have demonstrated log reductions exceeding 5.0 for pathogens such as Escherichia coli, Salmonella, and Listeria monocytogenes on food contact surfaces when treated with AEW.
Neutral electrolyzed water (NEW), another variant, operates at a near-neutral pH (6.0–7.5) while maintaining an ORP of 700–900 mV. This formulation reduces corrosion risks while retaining antimicrobial potency, making it suitable for prolonged use on stainless steel and other metals common in food processing equipment. Research indicates that NEW achieves comparable microbial reduction to chlorine-based sanitizers at concentrations of 50–100 ppm free available chlorine, without generating harmful disinfection byproducts like trihalomethanes (THMs).
Corrosion risks associated with EOW depend on the water chemistry, exposure duration, and material composition. Acidic electrolyzed water, due to its low pH, can accelerate corrosion in carbon steel and aluminum if not properly managed. However, stainless steel grades 304 and 316 exhibit high resistance to AEW when exposure is limited to short contact times (under 10 minutes). Neutral electrolyzed water presents a lower corrosion risk, with studies showing negligible weight loss in stainless steel even after extended immersion. To mitigate corrosion, facilities implement rinsing protocols post-sanitization and select materials compatible with the electrolyzed solution’s oxidative properties.
Operational cost savings with EOW systems arise from reduced chemical procurement, storage, and handling expenses. Traditional sanitizers like quaternary ammonium compounds (QACs) and peracetic acid (PAA) require bulk purchases, specialized storage conditions, and safety training for handling concentrated chemicals. In contrast, EOW systems generate sanitizer on-site using only water, salt, and electricity, eliminating the need for hazardous chemical inventories. A comparative analysis of sanitization costs in poultry processing plants revealed that EOW systems reduced annual chemical expenditures by 30–40%, with additional savings from decreased wastewater treatment needs due to lower residual toxicity.
Energy consumption of EOW systems varies by scale and design, with modern units optimized for efficiency. Small-scale generators consume approximately 2.5–3.5 kWh per cubic meter of AEW produced, while industrial systems leverage advanced membrane electrolysis to lower energy use. When benchmarked against thermal sanitization methods, such as steam cleaning, EOW systems demonstrate lower energy intensity, particularly in applications requiring frequent sanitization cycles.
Regulatory acceptance of EOW has expanded, with agencies including the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) approving its use as a no-rinse food contact surface sanitizer. This classification streamlines operational workflows by removing rinse steps mandated for some traditional sanitizers, further reducing water consumption and labor costs.
Despite these advantages, EOW systems require careful maintenance to sustain performance. Electrode fouling from mineral deposits can reduce efficiency over time, necessitating periodic descaling with citric acid or other mild cleaners. Water quality also influences system output; feed water with high hardness or organic load may require pre-treatment to prevent scaling and maintain consistent free chlorine generation.
In summary, electrolyzed hydrogen water systems provide a robust sanitization solution for food processing equipment, combining high antimicrobial efficacy with lower operational costs and reduced environmental impact compared to conventional sanitizers. Their adaptability to different water chemistries and material compatibility profiles makes them viable for diverse processing environments, provided corrosion risks are managed through appropriate material selection and process controls. As food safety regulations tighten and sustainability goals gain prominence, EOW technology is positioned as a key component of modern sanitization strategies.
The following table summarizes key performance metrics for EOW versus traditional sanitizers:
| Parameter | Acidic EOW (AEW) | Neutral EOW (NEW) | Chlorine-Based Sanitizers | Peracetic Acid (PAA) |
|-------------------------|------------------|-------------------|---------------------------|----------------------|
| pH Range | 2.0–3.0 | 6.0–7.5 | 6.0–8.0 | 2.0–4.0 |
| ORP (mV) | >1,000 | 700–900 | 600–800 | 900–1,100 |
| Microbial Log Reduction | ≥5.0 | ≥5.0 | ≥5.0 | ≥5.0 |
| Corrosion Risk | Moderate | Low | Low | High |
| Byproduct Formation | Minimal | Minimal | THMs, chloramines | Acetic acid |
| Operational Cost | Low | Low | Moderate | High |
This data underscores the competitive edge of EOW systems in balancing efficacy, safety, and cost-efficiency for industrial food processing applications.